The left atrial appendage (LAA) is a muscular pouch connected to the left atrium of a heart. Since the LAA lies within the confines of the pericardium and in close relation to the free wall of the left ventricle, its emptying and filling may be significantly affected by left ventricular function.
When patients have a normal heart rhythm, the atrial appendage squeezes rhythmically with the rest of the left atrium. In doing so, all of the blood in LAA is ejected into the left atrium and distributed all over the body, including the muscles, the organs, and the brain, with the rest of the blood from that chamber.
Atrial fibrillation is a common rhythm disturbance in older patients, in which the top chambers of the heart do not beat regularly. In a fibrillating atrium, the LAA becomes a major site of blood stasis, which significantly increases the risk of clot formation. Indeed, almost 15% of all patients with nonvalvular atrial fibrillation (NVAF) develop thrombus in their heart. For those who are at the highest risk for thromboembolic events, anticoagulation, including warfarin and the newer anticoagulants, has been offered. However, this is a difficult medication and patient compliance can be difficult. Dietary restrictions are necessary, the dose of the medication may need to be changed frequently, and blood testing is required at least once a month. In addition, anticoagulation increases the risk of both intracerebral and extracranial bleeding.
Approximately 30% to 50% of patients with atrial fibrillation are not even eligible to receive anticoagulation. In the recent years, several percutaneous LAA occlusion devices have been developed. The Percutaneous Left Atrial Appendage Transcatheter Occlusion (PLAATO) device (Appriva Medical) was the first to be tested and used in humans. Since then, multiple devices have emerged, including the Amplatzer device (AGA Medical Corporation/St. Jude Medical), the Watchman device (Boston Scientific), the WaveCrest device (Coherex), LAA occluder (Occlutech), and LAmbre device (Lifetech). A common characteristic of these devices is a relative large metal cage designed to self-expand and lodge into the LAA. It has been reported that a significant learning curve exists for physicians to adopt these treatments. Device-related embolization during or after the procedure and erosion of the device into the tissue are constant concerns for these implants
LARIAT suture delivery device (SentreHeart) differs from all the above implant devices—only a suture is used to tie-up the LAA. The LARIAT device is deployed by a trans-pericardial approach, specifically, by using an epicardial snare with a pre-tied suture to lasso and occlude the LAA. Both the intracardiac trans-septal access to the LAA and direct pericardial access are required. There are many access-related complications associated with the LARIAT device, including serious pericardial effusion and major bleeding.
Surgical techniques to occlude the LAA also continue to evolve, with efforts being made to overcome the inconsistent closure, tissue tearing, and intrathoracic bleeding associated with suturing or stapling techniques. For example, a widely used device, the AtriClip® (Atricure), consisting of a parallel titanium crossbar clip covered with woven polyester fabric, has received a CE Mark and is approved by the FDA for the closure of the LAA under direct visualization in conjunction with other open cardiac surgical procedures.
Thus, drawbacks in each existing LAA closure device/method continue to demand improvement on the LAA closure technology, such as an effective closure without post-procedure complications, minimum use of metal in the implant, and minimum invasion approaches with less recovery time.